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Gaussian FRET two-hybrid assays for determining the stoichiometry of hetero-oligomeric complexes in single living cells
摘要： Here we integrate multiple Gaussian-functions analysis into fluorescence resonance energy transfer (FRET) two-hybrid assays (Gaussian FRET two-hybrid assay) to determine the stoichiometric ratios of intracellular hetero-oligomers in single living cells. This method adopts in multiple Gaussian-functions to fit the E-count histograms of both donor- and acceptor-centric FRET efficiency (ED and EA) images of a single cell for obtaining the peak values (EDi and EAi), thus yielding the corresponding stoichiometric ratios (EDi/EAi) of intracellular hetero-oligomers. We performed Gaussian FRET two-hybrid assay for living Hela cells coexpressing different FRET tandem plasmids, and obtained consistent results with the expected values. Gaussian FRET two-hybrid assay for cells coexpressing Bad-CFP and Bcl-XL-YFP reveals that Bcl-XL binds with Bad to form a hetero-oligomeric complex with a stoichiometry of 2:1 on mitochondria.
关键词： Multiple Gaussian-functions analysis,FRET imaging,Single living cell,Stoichiometry,Hetero-oligomeric complex
更新于2025-11-21 11:24:58
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Non‐Stoichiometry Induced Switching Behavior of Ferroelectric Photovoltaic Effect in BaTiO <sub/>3</sub> Ceramics
摘要： Ferroelectric photovoltaic (FPV) effect has been studied among a series of non-stoichiometric BaTiO3 (Ba/Ti ? 0.92–1.05) ceramic chips prepared by tape casting method. The FPV performance increases abruptly when the Ba/Ti molar ratio deviates from the stoichiometry within 1%. Meanwhile, a photocurrent direction switching behavior is observed between Ti-excess and Ba-excess samples. The TEM analysis shows their significant difference in grain-boundary (GB), where abnormal GB with a width of 10–15 nm is observed in Ba-excess sample. The photocurrent switching phenomenon is described to the competition between the asymmetrical Schottky barriers induced PV effect and intrinsic FPV effect. Widen GB in Ba-excess BaTiO3 ceramics restrains the intrinsic FPV effect and results in the switching behavior. This study offers direct evidence of the vital role of GB in FPV effect and may promote the development of photovoltaic devices.
关键词： ferroelectric photovoltaic,barium titanate,non-stoichiometry,switching behavior
更新于2025-11-21 11:03:13
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Understanding doped perovskite ferroelectrics with defective dipole model
摘要： Leaf stoichiometry (nitrogen (N), phosphorus (P) and N:P ratio) is not only important for studying nutrient composition in forests, but also reflects plant biochemical adaptation to geographic and climate conditions. However, patterns of leaf stoichiometry and controlling factors are still unclear for most species. In this study, we determined leaf N and P stoichiometry and their relationship with soil properties, geographic and climate variables for Cyclocarya paliurus based on a nation-wide dataset from 30 natural populations in China. The mean values of N and P concentrations and N:P ratios were 9.57 mg g?1, 0.91 mg g?1 and 10.51, respectively, indicating that both leaf N and P concentrations in C. paliurus forests were lower than those of China and the global flora, and almost all populations were limited in N concentration. We found significant differences in leaf N and P concentrations and N:P ratios among the sampled C. paliurus populations. However, there were no significant correlations between soil properties (including organic C, total N and P concentrations) and leaf stoichiometry. The pattern of variation in leaf N concentration across the populations was positively correlated with latitude (24.46? N–32.42? N), but negatively correlated with mean annual temperature (MAT); meanwhile, leaf N concentration and N:P ratios were negatively correlated with mean temperature in January (MTmin) and mean annual frost-free period (MAF). Together, these results suggested that temperature-physiological stoichiometry with a latitudinal trend hold true at both global and regional levels. In addition, the relationships between leaf stoichiometry and climate variables provided information on how leaf stoichiometry of this species may respond to climate change.
关键词： N:P ratio,geographic variations,nitrogen,climate variables,Cyclocarya paliurus,phosphorus,natural populations,leaf stoichiometry
更新于2025-09-23 15:23:52
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Supramolecular Design of Donor-Acceptor Complexes via Heteroatom Replacement towards Structure and Electrical Transporting Property Tailoring
摘要： A feasible strategy relies on using heteroatom replacement which is namely chemical modification to the organic compound. Here we present this design concept for donor-acceptor complexes, which involves introducing nitrogen atoms to the middle ring of donor molecules to promote short contacts and reduce steric effect of the mixed framework. These nitrogen modified complexes are able to possess shorter molecular distance besides the mixed stacking pathway, enlarged π–π interactions or even a scarce 1:2.5 molar ratio through extra acceptor insertion. As a result, the unique 1:2 complex with nitrogen atoms on the different sides demonstrated stable electron field-effect mobility performance, while the binary system with no nitrogen replacement or N atoms on the identical side displayed poor ambipolar properties. These results confirmed that the heteroatom replacement is a powerful molecular design tool to fine tune the molecular packing of organic donor-acceptor complexes and their corresponding electronic properties.
关键词： Theoretical Calculation,Electron Transport,Heteroatom Replacement,Supramolecular Design,Short Contacts,Stoichiometry Varying
更新于2025-09-23 15:19:57
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Systematic Study of the SiOx Film with Different Stoichiometry by Plasma-Enhanced Atomic Layer Deposition and Its Application in SiOx/SiO2 Super-Lattice
摘要： Atomic scale control of the thickness of thin film makes atomic layer deposition highly advantageous in the preparation of high quality super-lattices. However, precisely controlling the film chemical stoichiometry is very challenging. In this study, we deposited SiOx film with different stoichiometry by plasma enhanced atomic layer deposition. After reviewing various deposition parameters like temperature, precursor pulse time, and gas flow, the silicon dioxides of stoichiometric (SiO2) and non-stoichiometric (SiO1.8 and SiO1.6) were successfully fabricated. X-ray photo-electron spectroscopy was first employed to analyze the element content and chemical bonding energy of these films. Then the morphology, structure, composition, and optical characteristics of SiOx film were systematically studied through atomic force microscope, transmission electron microscopy, X-ray reflection, and spectroscopic ellipsometry. The experimental results indicate that both the mass density and refractive index of SiO1.8 and SiO1.6 are less than SiO2 film. The energy band-gap is approved by spectroscopic ellipsometry data and X-ray photo-electron spectroscopy O 1s analysis. The results demonstrate that the energy band-gap decreases as the oxygen concentration decreases in SiOx film. After we obtained the Si-rich silicon oxide film deposition, the SiO1.6/SiO2 super-lattices was fabricated and its photoluminescence (PL) property was characterized by PL spectra. The weak PL intensity gives us greater awareness that more research is needed in order to decrease the x of SiOx film to a larger extent through further optimizing plasma-enhanced atomic layer deposition processes, and hence improve the photoluminescence properties of SiOx/SiO2 super-lattices.
关键词： plasma-enhanced atomic layer deposition (PEALD),stoichiometry,SiOx,SiO2,superlattice
更新于2025-09-19 17:15:36
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Elucidating the Pulsed Laser Deposition Process of BiVO <sub/>4</sub> Photoelectrodes for Solar Water Splitting
摘要： BiVO4 thin films for the use as photoelectrodes for solar water splitting are prepared by pulsed laser deposition (PLD), a powerful technique to synthesize compact multinary metal oxides films with a high electronic quality. Here, the PLD process of BiVO4 films by ablating a BiVO4 target is systematically elucidated with a special focus on deviations from an ideal stoichiometric target-to-substrate material transfer. By correlating the V:Bi ratio of the films with their charge carrier transport properties and PEC performance, AM1.5 sulfite oxidation photocurrents of ~2.4 mA cm-2 at E = 1.23 V vs. RHE with stoichiometric films are achieved without any deliberate doping or surface modification. In addition, we prepare BiVO4 photoelectrodes for the first time by the alternating ablation of Bi2O3 and V2O5 targets. This approach is found to be an attractive alternative route to control the cation stoichiometry and produces BiVO4 films that generate AM1.5 sulfite oxidation photocurrents of up to 2.6?mA cm-2 at E = 1.23 V vs. RHE. Our results provide important insights into the PLD process of ternary oxide semiconductors and help to accelerate the synthesis and investigation of new multinary metal oxide photoelectrodes.
关键词： pulsed laser deposition,solar water splitting,stoichiometry,BiVO4,photoelectrodes
更新于2025-09-19 17:13:59
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High-current density and high-asymmetry MIIM diode based on oxygen-non-stoichiometry controlled homointerface structure for optical rectenna
摘要： optical rectennas are expected to be applied as power sources for energy harvesting because they can convert a wide range of electromagnetic waves, from visible light to infrared. the critical element in these systems is a diode, which can respond to the changes in electrical polarity in the optical frequency. By considering trade-off relationship between current density and asymmetry of IV characteristic, we reveal the efficiency limitations of MIM diodes for the optical rectenna and suggest a novel tunnel diode using a double insulator with an oxygen-non-stoichiometry controlled homointerface structure (Mox/ Mox?y). A double-insulator diode composed of pt/tio2/tio1.4/ti, in which a natural oxide layer of tio1.4 is formed by annealing under atmosphere. The diode has as high-current-density of 4.6 × 106 A/m2, which is 400 times higher than the theoretical one obtained using Pt/TiO2/ti MiM diodes. in addition, a high-asymmetry of 7.3 is realized simultaneously. These are expected to increase the optical rectenna efficiency by more than 1,000 times, compared to the state-of-the art system. Further, by optimizing the thickness of the double insulator layer, it is demonstrated that this diode can attain a current density of 108 A/m2 and asymmetry of 9.0, which are expected to increase the optical rectenna efficiency by 10,000.
关键词： optical rectenna,oxygen-non-stoichiometry controlled homointerface structure,high-asymmetry,high-current density,MIIM diode
更新于2025-09-19 17:13:59
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Low damage patterning of In <sub/>0.53</sub> Ga <sub/>0.47</sub> As film for its integration as n-channel in a fin metal oxide semiconductor field effect transistor architecture
摘要： One of the challenges of InGaAs integration as a channel in a fin field effect transistor architecture is the patterning of the III–V fin with nanometer scale definition, vertical sidewalls, and undamaged surfaces. In this work, the authors propose a two-step process to etch anisotropically and with minimal damage thin layers of InGaAs material. The first step of the process aims to modify the InGaAs surface on a well-defined thickness with limited sputtering by implanting light ions generated by a low pressure He/O2 plasma. The depth of the material modification is well controlled by the ion energy and saturates with process time, giving to this step a self-limited behavior. The second step uses aqueous HF solution to remove the modified oxidized InGaAs layer with infinite selectivity over the nonmodified InGaAs layer. The repetition of cycles of the two-step process was applied to etch the thin film of InGaAs as well as pattern using a SiN hard mask. Blanket experiments show that each cycle of the two-step process allows to remove a fixed and reproducible InGaAs thickness of 5.7 nm, while blanket SiN films are not consumed. After the process, the InGaAs surface roughness is kept intact, but the surface stoichiometry is slightly degraded with Arsenic enrichment because of the wet chemical reactions between the III-As semiconductors and the acids. The results on the pattern show that it is possible to transfer the SiN hard mask into the InGaAs layer using cycles of the two-step process with a reproducible consumed InGaAs thickness at each cycle and low sidewalls surface damage. However, the process leads to tapered InGaAs profile because of the lateral consumption of the SiN hard mask due to preferential sputtering at grazing incidence angle.
关键词： FinFET,atomic layer etching,stoichiometry,plasma etching,InGaAs,surface damage
更新于2025-09-10 09:29:36
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Reference Module in Chemistry, Molecular Sciences and Chemical Engineering || 2D Ternary Oxide Layers: New Paradigms of Structure and Stoichiometry
摘要： Two-dimensional (2D) oxide materials have tremendous potential in fundamental research and cutting edge technologies owing to their outstanding physical and chemical properties, which makes them excellent candidates for a wide range of applications including power harvesting, hydrogen storage, fuel cells, gas sensors, advanced electronic and spintronic devices, and nanocatalysis.1,2 To gain a fundamental understanding of the novel properties, afforded by the reduced dimension of oxide nanostructures, structurally well-defined model systems have been utilized, typically in the form of ultrathin oxide films (with a thickness of one to few atomic layers) epitaxially grown on single-crystal metal surfaces. Emergent phenomena in their geometric architecture, electronic and vibrational structure, chemical nature and magnetic behavior have been recognized,3–8 rendering oxide nanolayers vast and unforeseen opportunities in science and technology. To date, most of the studies have been focused on binary 2D oxides, but the increased interest in more complex oxide materials, such as ternary or multicomponent oxides with a broader range of functionalities, requires an adequate understanding of their properties at the nanoscale, which is still scarce. Even for high technologically important ternary oxides, such as the perovskites, there are only few studies reporting on the preparation of 2D oxide layers on metal supports, which are found to display unique structural behavior with no counterpart in the bulk.9,10 One reason for this is that the preparation of ternary oxide nanolayers with well-defined structure and stoichiometry is more challenging than for binary oxides, which requires the development of new fabrication strategies, where suitable thermodynamic and kinetic parameters have to be optimized in a narrow multiparameter space to obtain structures with desired stoichiometry and 2D morphology. Moreover, the elucidation of their structural properties at the atomic level is experimentally and theoretically more demanding than for the binary oxides.
关键词： stoichiometry,surface science techniques,2D ternary oxide layers,structure,metal tungstates
更新于2025-09-10 09:29:36
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CHARACTERIZATION OF NEW NON-STOICHIOMETRIC FERROELECTRIC (Li0.95Cu0.15)Ta0.76Nb0.19O3 AND COMPARATIVE STUDY WITH (Li0.95Cu0.15)Ta0.57Nb0.38O3 AS PHOTOCATALYSTS IN MFCs
摘要： This work investigates the photocatalytic activity of new ferroelectric material with formula (Li0.95Cu0.15)Ta0.76Nb0.19O3 (LT76) in a single chamber microbial fuel cell (MFC) and compare its performance with the similar photocatalyst (Li0.95Cu0.15)Ta0.57Nb0.38O3 (LT57). The photocatalysts LT76 and LT57 were synthesized by ceramic route under the same conditions, with the same starting materials. The ratio Ta/Nb was fixed at 4.0 and 1.5 for LT76 and LT57 respectively. These phases were characterized by different techniques including X-Ray diffraction (XRD), transmission electronic microscopy (TEM), particle size distribution (PSD), differential scanning calorimetric (DSC) and UV-Vis. The new photocatalyst LT76 presents specific surface area about 0.791m2/g and Curie temperature of 1197°C. The photocatalytic efficiency of this material is evaluated in terms of wastewater treatment and electricity generation by power density and removal rate of chemical oxygen demand (COD) in the presence of a light source. The values of the maximum power densities and COD removal were 19.77 mW/m3 and 93% respectively for LT76.
关键词： microbial fuel cell,non-stoichiometry,ferroelectric,Lithium niobate-tantalate,photocatalyst
更新于2025-09-09 09:28:46